Regenerative furnace.



J. E. BELL.

REGENERATIVE FURNACE. I

APPLICATlON mp0 JUNE 2, 1913.

1,170,397., Patented Feb. 1, 1916.

3 SHEETSSHEET l- QQQ a i I M2751; 4 6,4644% v \QMRWQ J. E. BELL.

REGENERATIVE FURNACE. APPLICATION FILED JUNE 2, 1913.

1,170,37. v Patented Feb. 1, 1916.

3 $HEETSSHEET 2.

INVENTOFI a W m J. E. BELL.

REGENERATWE FURNACE. APPLIICATION FILED JUNE 2f1913.

1,176,89? Patented Feb.1,l916.

3 SHEETS-SHEET 3.

WITNESSES IIIINVEN'i'OR' QTNE Q g 6. AQZA/ q W W CLUE;

UNITED sT rEs PATENT OFFICE. T

JOHN E. or new YORK, N. Y.

nnennnnnrrvn FURNACE.

Specification of Letters Patent.

. .PatentedFeb.1,1916.

Application filed June 2, 1913. Serial No. 771,189.

To all whom it may concern Be it known that I, JOHN E. BELL, a citizenof the United States, residing at New York, in the county of New. Yorkand State of New York, have invented a' new and useful Improvement inRegenerative' Furnaces, of which the followin isa full,

clear, and exact description, re erence being had to the accompanyingdrawings,

forming part of this specification, in which:

- Figure 1 is a vertical longitudinal section Fig.

' open-hearth furnace in vertical section, and

of an open hearth furnace showing one form of my invention; Fig. 2 is apartial longitudinal section showing a modified form;

Fig. 3 is a longitudinal section showing an other 'form of the inventionFig. l is a cross section on the line IVIV of Fig. 3; and Figs. 5 and 6are detail views of a refractory shutter hereinafter referred to. 7 is aview showing a portion of an also showing, more or less conventionally,

.; used or experimented with-as, fuel for fur nac'ej pf this class,ithasf'been ffdifiused b hl i fi l- 1 q -Q p fl i "and low i the Wa m iapp y; 1 athe P in w ere i itsenters the]furnacejclianib'er, To 1 onearrangement of fans for producing both forced and induced draft in theregenerators.

My invention relates to the class of'regenerative heatingormetallurgical furnaces requiring a high temperature and is designed toincrease the fuel economy, re

duce'the space occupied, and to permit more perfect control of thefurnace as to tem.-'

perature and character of the'flame or heat. It provides a new systemfor utilizing as fuel pulverized coal which need not be crushedorg'r'ound to. the'finen'ess heretofore necessary. It provides forpreheating 'all the air used for combustion from heat ab-' stracted fromthe waste gases. the location, structure and arrangement of Itimprovesthe regenerators, making; them 'more effective in their function ofcooling the waste gases, and-returningfthe heat sogained to' the cycle;It improves and makes: more flexible the present draft"arrangementsandprovides for variation in, theair'jsupply .as

between primary and f secondary air as. well I as the :twojjo1ntly..;-,'Itjpermit's combining in v one. s ruct re t he fi ne eith g'ga Pducers and reg'eneratdls and, eliminates f'the lossesincident to buildin'jthem separately.

Heretofora'fl when pow e'red coal {has "been duce a similar flame.

consumed while in suspension.

products of combustion then flow nto'the "one or "more fw successfully,the mixture of powdered coal and cold air must behave as a gas and pro-This necessitates that the coal be dried and reduced to an almostimpalpable powder. It must be crushed,

dried and then' ground. This requires a large plant of expensive;machinery which uses a great amount of power in operation and istroublesome tomaintain; The cost of preparmg fuel in this way is in manyinstances prohibitive. In addition, there is a potentlal'loss in usingcold air for blowing the fuel into the furnace, as for maximum economythe entire air supply should be heated from the waste gas. Further,there is no way of separating the ash from the I gases of combustion andit must find its way lnto the furnace or regenerator passa es, where, ineither case, its presence 1s ob ectiOnable.

In accordance with my inventio n, I propose to pulverize coal withoutdrying in] one operation, and to burn this pulverized coal within achamber distinct and separate from the furnace chamber while insuspension in an atmosphere of preheated air,

or preheated air and superheated steam.

.This chamber is preferably so arranged that the air and fuel pass downvertically through it, and is of a height sufiicient to give the largerparticles of fuel time to be The hot furnace and a secondary combustionmay be efl'ected by introducing auxiliary air, pref-f erably heated',-atthe point where the prod- ,ucts enter the furnace port.

"To limit the rise in temperature 1n the separate combustion chamber andthus reduce 'destructivei'action on the brickwork, I

may either introduce steam, which will ab- 'sorb a considerable amountof heat in its decomposition, .or .I may absorbfa portion of this' heatby water-heatingsurface suit abl {located in? ofiformiiig apart of the"wet 1 of thisichamber', or Inlay use both- 1f less than thatrequired-for complete' combustion. In" the second or alternative method,

alls -of the combustion 1;;

-. introduce steam or steam and air,

- generators is 20 chamber will contain or be formed of waterheatingsurfaces and these surfaces will d1- rectlyabsorb. the heat radiatedfrom the fuel during combustion and thus hold down the temperature toany desirable point. The amount of these water-heating surfaces which isexposed may be adjusted by means hereinafter described. I alsopreferably turn the gases of combustion through a sharp angle at thebottom of the combustion chamber to collect the ash and unburnedparticles of coal on a suitable grate at this point, and under thisgrate I may asin the usual gas producer method. This will aid inconsuming any unburned carbon and prevent the formation of hard clinker.

The present practice in constructing reto arrange thepassages andcheckerwork so that the draft produced by the columns of hot airbringstheair needed for combustion into the furnace chamber.

This requires that theregenerator passages be designed not only toproduce the draft,

but also to give small obstruction to'its flow.

However arranged, the checker chambersmust be below the furnace. Ipropose to force the air through there'generators by a fan or steamblower or. by other suitable means. .I can on this account locate theregenerators wherever desired, but I preferably locate them above thefurnace.

I have discovered that the rege-nerators commonly used with thesefurnaces arevery ineffective and that this is in large part due to thelow velocity of the. gas and air through the passages. Other thingsremaining the same, the rate of transfer of heatin a re- 7 directlypropor- 40 tional to the velocity of the gas. I therefore generator willbe nearly preferably make my regenerators of flat rectangular tileplaced on edge and by bringing them together or placingthem fartherapart,

whereas a mixin or eddy flow is necessary for rapid heatjtrans fer. By am1xmg'?.or eddy flow, I mean that the gas has the internal motions madevisible in dense-smoke rolling from the top of a stack. A direct orstream. line flow will break 'down'into this motion at suflicientlyhighvelocities.. This criticalvelocity 1s inverselyproportional to the widthof the gas passages. The narrower the passages, the greater the criticalvelocity. To insure the eddy or, mixing flow, I prefer on this accountto obtain the high velocity by dividing my regenerator into a number ofpasses by partition walls or baffies, rather than by reducing the areaof thegas passages. In arranging my regenerators, I first select theshape and the size of the opening and then make at least a suficlent Table refractory dampers 12, 12.

tra es? number of passes .to insure a mixing flow in every pass.

struction gives a weight of gas per hour per square foot of flue area ofless than one thousand pounds and probably averages nearer five hundredpounds. I preferably raise this to from two thousand pounds to fourthousand pounds. I have also found that irregular or tortuous passagesdo not increase the heat transfer in a mixed or eddy flow and since theyobstructv the draft, I therefore preferably arrange my regenerators withstraightsmooth passages which fact, taken in conjunction with the shapeof the tile, makes it possibleto put a great deal more absorbingsur'facein a given space than heretofore.

In the drawings, referring to the form of Fig. 1, 2 represents an openhearth furnace having the usual end ports 3, 3 Above the top of thisfurnace, I build a pair of regenerative chambers 4, 4 divided into aseries of passes. In the form shown, each. pass is divided into separatepassages by a partition The present-tpractice-in regenerator conwall. Atthe ends ofthe regenerators, I lodividing ridge 1 0, and suitable,seatsin the stack ports, to direct the-entering air into one of theregenerators and the gases from the other regenerator to the stack orfan.

The up and down passes in the regenerators are marked a," b, 0 and d.From one of these passes, 1 preferably by-pass'a portion of the airthrough channels 1-1, or 11, taking 'it' direct to the furnace port.This auxiliary or secondary air may be controlledby suitis usedto limitthe rise in temperature, I may feed steam in at any suitable point ofthe regenerator, for instance, by use of. the steam ets shown at 13and13*,or Imay use the steam to blow, the fuel into the combustion-chamber.

In the chambers 14,- 142 below the combustion chambers, I preferablyprovide grates 15, 15 with steam jets 1 6,.16 beneath them.-

Unconsumed' coa'l, will drop on these grates and under the grate Ipreferably introduce steam or steam and air as in usual gas producerpractice. 1

The numerals 17, 17 represent coal feeders, which preferably drop thecoal in a sheet or curtain the full width of the combustion chamber, thecoal, of course, beingfedalter- If steam nately first in one'combustionchamber" and then into the other during the reversals.

" of powdered coal, dropping through the 'right hand feeder. Thiscoal-burns in susone, with valves in the position shown in Fig. '1. Thisair flows through the reduced sized channels of the regenerator, and theprimary air enters the top of the combustion chamber and flows down withthe sheet pension during its descent, any unconsumed particles droppingon the right hand grate as the products reverse the direction of flow 1nthe chamber 14*. Leaving the furnace,

the products of combustion pass through the other combustion chamber '5,which now forms an outlet flue and thence through the left-handregei'ierator. Owing to the presence of both forced and induced draft,the an flows at considerable velocity through one regenerator, andsimilarly the products of combustionthrough the other regenerator,whence they pass to the stack. The

secondary air taken from either re'generator through the bypass entersthe hot gas at the entrance of the furnace and sets up secondarycombustion. In this arrangement, the combustion chamber and regeneratorare combined in one structure. There 15 no chance for cooling of the gasbetween the combustion chamber and furnace or 'between the furnace andregenerators. Both the primary and secondary air'are heated from theregenerators and the steam used in the producers as well."

t In Fig. 2, I show a portion of a furnace SHIlllil-lt to that of Fig.1, except that instead of linnting the rise in temperature by adjmitting steam, I provide water-heating surface for this purpose. In thiscase, the end walls 18 forming the side walls of the combust onchambers, are provided with waterheating surfaces in the form of watertubes 20. These tubes may form part of a boiler of any desired type, andin the form Shown,

I provide upper and lowerheaders 21 and 22, which the pipes enter. Fromthe upper heade1 connecting pipes 23 lead to a steam and water drum 24,from which a tube or tubes 25' exterior to the furnacelead down 'chamberthus giving economy of space and construction cost. I may, however,place the regenerators; at one'side of and below the furnace. Thus,inFigs. 3 and 4, I show 29, having a-struc ture wherein a horse-shoefurnace 28 is provided, the fuel-and gas being fed in and out on thesame side of the furnace.

In this case, the regenerators-4 and 4 are located side by side at oneside of and be- .low the furnace chamber. In these figures,

parts similar to those in Fig. 1' are indicated by similar numerals withthe letter c applied. V i

In order to still. further regulate the temperature in the combustionchamber, I may also use a damper system in connectlon with water-heatingsurface. Thus, in Figs. 5 and 6, I show a portion of a refractoryshutter spaced apart tiles '30, projecting therefrombetween the watertubes, such as shown at 20 in Fig. 2. The shutter may be moved back andforth to expose. more or less of the heating surface to the heat, thusregulating the amount of heat absorbed by the Water tubes. By usingthese movable projecting tiles and, varying the amount of,

steam fed in and the proportions of the primary and secondary air, aswell as the amount of fuel, full control can be had over the temperatureand the flames. By sharply turning back the gases of combustion at i thebottom of the curtain wall at the-end of" the combustion chamber. theash and unburnt particles of coal will 'be dropped out sume any unburntcarbon and at the same time avoid the formation of a hard clinker.

It Willbe noted that, in effect, I provide a regenerator furnace with agas producer intermediate its regenerators and the furnace chamber,since the action which takes place in the primary or preliminarycombustion chambers is the formation of a producer gas from the powderedfuel. In the operation of regenerative furnaces, it is not onlydesirable to obtain as perefect a degree of combustion as possible, butthe production of a long controllable flame in the furnace chamber isalso essential. By forming a combustible gas in the preliminarycombustion' chamber and by burning the powdered .fuel in a controllingsupply of hot air from the regenerators under certain conditions inwhich producer reactions occur,

I obtain both these desired results in an efficient and highlyeconomical manner.

The advantages of my invention will be appreciated by those skilled inthe art.

- The process gives great economy of fuel,

. a low stack temperature and highly efficient combustion. The transferof heat to and from the checkerwork of the regenerators is enhanced andthe control of temperature and flame is greatly improved. Heat lossesare reduced and economy in space andoriginal cost of the structure isreduced.

Many changes may be made in the form and arrangement of' theregenerators, the

we a

furnace, coal feeders, etc., without departing from. my invention.

- Certain features of my' invention may also be used with or without theother features within the scope of my claims.

I claim? 1. The herein described method of oper-h ating regenerativefurnaces, which consists 1n preheating an in a regenerator, then feeding powdered coal to and burning it in the" preheated air between theregenerator and the furnace chamber'under conditions which cause aproducer reaction to form a combustible gas, and then passing this gasinto the furnace for further combustion,substantially as described.

2. The method of operating regenerativ furnaces, consisting in heatingair in aregenerator, dividing. said heated air, feeding pulverized fuelinto one portion of the air and burning the same under conditions whichcause a producer reactionbetween the regenerator and the furnace chamberto form a combustible gas, and then supplying the L feeding this gasintoa furnace, and limiting the rise in temperature in ,the combustionchamber, substantially as described.

4.. The method of operating'regenerative furnaces, which consists inheating the air in a regenerator, feeding pulverized solidfuel-into aportion of said air, burning the fuel in' suspension in said air betweenthe regenerator and the furnace chamber toforin a combustible gas, andthen'supplying another portion of heated air to said gas,

and-limiting the rise in temperature in the combustion chamber,substantially as de: scribed. 4

5. The method of operating. regenerative furnaces, which consists inheating. air in a chamber separate from the furnace chamber, and thenpassing saidgas into the furnace- 55.

'regenerator, supplying a pulverized solid fuel to the heated air andburningvthe same to form acombustible gas in a combustion chamber forfurther combustion, and. chang-' ing the direction offlow of the gasbetween q-the' combustion chamber, and v the furnace chamber for, thepurpose of causing the gas to deposit ash, substantially as described.

6. The hereindescribed-method of operating regenerative-furnaces, whichconsists in heating air in a regenerator' of the fur-' nace, feedingpulverized solidfuel into the heated air, and burning said fuel to ,forma combustible gas in a combustion chamber between the regenerator andthe furnace chamber, passing said gas from "thecombustion chamber intothe furnace-chamber, and taking the gases from the furnace chamberthrough the regenerator, substantiallyas described. i

' 7.- The method of operating regenerative furnaces, which consists inheating air m a regenerator, feeding pulverized solid fuel into thepreheated air and burning thismixture in a combustion chamber outside ofthe furnace chamber to form a combustible gas,

supplying steam-It'o'the combustion chamber to limit the temperaturetherein, and

then feeding the combustible gas into the furnace chamber, substantiallyas described.

8 The method of operating regenerative furnaces, which consists inheating air in a regenerator, feeding pulverized solid fuel into thepreheated air and burning this mixture in a combustion chamber? outsideof the furnace chamber to forma combustible gas,

supplying steam to the combustion'chamber to limit the temperaturetherein, then fee'd- .ing the combustible gas into the furnace chamber,and supplying a further portion of hot air to said combustible: gas,substan i tially as described.

9., The method of operating regenerative furnaces, consisting.in-heating air in a re-' generator, feeding the pulverized fuel into saidheated air, feeding the burning mixture 1 through a vertical combustionchamber,

changing the direction of flow of the mix ture, thenfeeding afurthersupply of hot air into the mlxture and passing the same into thefurnace, substantially as described. 1 I

. '10. The method of operating a regenerative' furnace, which consistsin forcing air I through a regeneratorfto preheat the air,

mlxingpulverized solid fuel withthe preheated air, and burningthemiXture between 2 Y the regenerator and the furnace'chamber to form acombustible gas, andfdrawing the products of combustion from 1the-furnace chamber through the regeneratorby'induced draft,substantially as described.

11. A regenerative, furnace. having a re- I generator, apreliminary"combustion chamber located-between the regenerator and thepowdered fuel into the upper portion of said chamber and causing it to;fall by gravity therein, means for 'supplyingpreheated air;

to said. chamber, means for furnishing a further supply of air to thefurnace chamber proper, and means for causing the combustiblegas formedin the preliminary. chamber to change itscourse in passing fromthepreliminary chamber to the furnace chamber and thereby-causing it todeposit its containedash, substantially as, described.

12. In the operating ofregenerative-furnaces, the step consisting offorcing air or gases through a regenerator andthence a 5 furnace chamberproper, means for feeding l through the furnace chamberyand' drawingthem by induced draft through the other regenerator, and maintaining avelocity of at least two thousand pounds of gas per hour per square footof sectional area through the hotter parts of the regenerator,substantially as described.

13; A regenerative furnace having a preliminary combustion orgasification chamber located between the regenerator and the furnacechamber of the furnace, means for supplying heated air from theregenerator rate combustion chamber located between a regenerator andthe furnace chamber proper, means for supplying heated air from theregenerator to said chamber, means for feed ing pulverized solid fuelinto said chamber, and a pressure blower arranged to force airthrough'the regenerator, substantially as described.

15. A reversing regenerative furnace having a combustion or gasificationchamber located between each of its regenerators and the furnacechamber, means for supplying heated air from the regenerators to saidchambers, and means for feeding powdered solid fuel into each of saidchambers, substantially as described.

16.- A reversing regenerative furnace having a combustion orgasification chamber located between each of its regenerators and thefurnace chamber, means for supplying heated air from the regenerators tosaid chambers, and means for feeding powdered solid fuel into each ofsaid chambers, ,to gether withmeans for limiting the rise in temperaturein said chambers, substantially as described.

17. A reversing regenerative furnace having a combustion or gasificationchamber located between each of its regenerators and the furnacechamber, means for supplying heated air from the regenerators to saidchambers, means for feeding powdered solid fuel into each of saidchambers, a .pressure blower arranged to force .air through theregenerators, and a 'suction'fan' arranged to draw the hot gases throughthe regenerators, substantially as described.

18. A regenerative furnace having a vertically extendingcombustionchamber located between its regenerators and 'the furnace chamberproper, and means for feeding pulverized fuel and hot air through saidcombustion chamber toform a combustible gas therein, substantially asdescribed.

19. A regenerative furnace having a vertically extending combustionchamber located between its regenerators and the fura pair of pulverizegas therein, the connection between said chamber and the furnace chamberhaving a turn therein to change the direction of flow of gases inpassing from the combustion chamber into the furnace chamber,substantially as described.

20. A regenerative furnace having a vertically arranged combustionchamber between its regenerators and the furnace chamber proper, meansfor supplying hot air to said chamber from the regenerators,

and means for feeding powdered fuel into the upper portion of saidchamber whereby the fuel may be burned while in suspension in the heatedair in said chamber to form a combustible gas, substantially asdescribed,

21. A regenerative furnace having a combustion' or gasification chamberbetween its regenerators and the furnace chamber proper, means forsupplying heated air to said chamber from the regenerators, means forsupplying powdered fuel to said cham- -;;ber, and means for supplyingadditional heated air from the regenerators to mix with L-thecombustible gas formed in said chamber before said gas enters thefurnace chamber proper, substantially as described.

22. A single furnace structure having a furnace chamber, a regenerator,and a pulveri'zed fuel combustion chamber intermediate the regeneratorand the furnace chamber substantially as described.

23. A single furnace structure having a furnace chamber, a air ofregenerators and fuel combustion chambers combined in the samestructure, and located between the regenerators and the furnace chamber,the combustion chambers having pulverized fuel feeders, substantially asdescribed. A

24. A regenerator having eachof its passes divided into a plu'ralityofparallel flues, and fan means for maintaining a velocity equal to atleast two thousand pounds of gas per hour per square foot. of sectional'free area in each pass, substantially as dedescribed.

26. A regenerator having each of its passes divided into a plurality ofvertical parallel flues, and fan means for maintaining a We? locityequal to at least two thousand pounds of gas per hour per square foot of'sectlonal free area in each pass, substantially as described. 27. Afurnace having a serial pass regenerator through which the waste gasesflow through all ofthe passes, and means whereby both the primary andsecondary air are heated together in the earlier of said passes and theprimary air is further heated in the final passes, substantially asdescribed.

28.- A furnace having a serial pass rein the final passes, substantiallyas described.

I rality of fiues in each '29. A regenerator having'a plurality of.successive up and down passes, and a pluass, and means for maintaining-avelocity in said passes equal to at' least two thousand pounds persquare set my hand.

. Witnesses I imes? foot of free sectional area in each pass,substantially asdescribed. I

30. A single furnace structure having a furnace'chamber, a regenerator,and a pulverized fuel combustion chamber therein, and the regeneratorhaving serial passes through all of which the waste gases fiow,

with means whereby upon reversal vboth the primary and: secondar j airare heated to gether in the earlier or said passes, and-the primary airand steam is further heated in the final passes, substantially asdescribed.

In testimony whereof, I have hereunto JOHN EBELL.

, M. Mt'imER, v WALTER BALMFORD.

